Goals from James Coppinger, a Niall Mason penalty and Andy Butler earned Rovers consecutive League One wins for the first time this season
Ferguson said: “If you can imagine a game going as well as it possibly could have then that was one of those.
“We were very comfortable, got a clean sheet, got three goals and could have had more.
“I thought we managed the game very well.
“I’m very pleased with the players. At this stage of the season it is all about picking up points.
“I’m not too bothered about how good the performances are at this period of the year, it’s just about getting the results.”
Butler, Ben Whiteman and Tommy Rowe all went close to giving Doncaster the lead before Coppinger did, bundling in from close range in the 33rd minute after John Marquis and Alfie May both had efforts saved.
Matt Grimes clipped Marquis from behind in the box and Mason drilled home the penalty to make it 2-0 on 43 minutes.
Doncaster put the game to bed in the 66th minute when Butler forced the ball home after a Mathieu Baudry header was cleared.
Doncaster: Lawlor, Mason, Baudry, Butler, Garrett, Whiteman, Kongolo (Blair 61), Rowe, Coppinger, Marquis, May (Beestin 83). Unused substitutes: Alcock, Marosi, Mandeville, Wright, Houghton.
Northampton: Ingram, Moloney, Poole, Taylor, Buchanan, Shaun McWilliams (Hanley 69), O’Toole (McGugan 56), Grimes, Foley, Richards, Long (Hoskins 56). Unused substitutes: Cornell, Kasim, Waters, Smith.
Referee: B Toner (Lancashire).